Genetic variation and phylogenetic analyses reveal transmission clues of Lentinula edodes partitivirus 1 (LePV1) from the Chinese L. edodes core collection

Lentinula edodes partitivirus 1 (LePV1), a new mycovirus possibly responsible for serious morphological deformities during L. edodes cultivation, is widespread in the Chinese L. edodes germplasm. Here, LePV1 isolates from the Chinese genetically-diverse L. edodes core collection were identified to be highly conserved and devoid of codivergence between virus and its hosts. Phylogenetic analysis showed that the LePV1 isolates could be grouped into two distinct clades (subtype I and subtype II), without geographical bias in the composition of this population. Compared with the other LePV1 isolates, one non-synonymous variation was observed in the LePV1 isolate from the symptomatic strain SX12. Purifying selection appears to be the main evolutionary force acting on LePV1 and it may be subject to negative selection. Based on the aforementioned results, the domestication history of L. edodes in China and the high frequency of virus incidence in basidiospores, we postulate that LePV1 may exist in nature and have had relationship with L. edodes wild strains since early times. Moreover, wind-blown spores carrying LePV1 may play an important role for the transmission of LePV1 in nature, while artificial activities such as vegetative propagation and hybridization breeding may also transmit virus from wild strains to cultivated ones.